This invention relates to a variable displacement blower and, in particular, to a blower having a displacement that can be varied without changing the blower speed. More specifically, this invention relates to a blower that is ideally well suited for use in conjunction with a Stirling engine.
The Stirling engine is a highly efficient external combustion engine that typically utilizes a pair of opposed pistons contained within a sealed cylinder. The pistons are operatively connected by means of a regenerator. Because the pistons are sealed within the cylinder, they require both an auxiliary source of heat and an auxiliary source of air in order to sustain the operation of the engine. Generally an air blower is utilized to bring ambient air into the high temperature sections of the engine in sufficient quantity to support fuel combustion. Many Stirling engines employ high speed centrifugal blowers for this purpose which are driven from the engine through a hydraulically controlled transmission which is more commonly referred to as a variator. A servo-motor driven air throttle valve is also generally needed in conjunction with the blower in order to obtain fine control over the air supply as it moves into the engine. In any event, the auxiliary equipment is generally extremely complex and bulky and has proven to be difficult to maintain over extended period of time.